#include <set>
#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;

int n;
vector<int> children[200100];
int bit[200100];

long long dfs(int i) {
    long long sum = 0;
    for (int x = i+1; x <= n+1; x += x&-x) bit[x]++;
    for (int j : children[i]) {
        for (int x = j+1; x > 0; x -= x&-x) sum += bit[x];
        sum += dfs(j);
    }
    for (int x = i+1; x <= n+1; x += x&-x) bit[x]--;
    return sum;
}

int main () {
    cin >> n;
    for (int i = 1; i < n; i++) {
        int p; cin >> p;
        children[p].push_back(i);
    }
    cout << dfs(0) << endl;
}